TH400 Leakage questions

[72step]

I have a TCI racing TH400 tranny which was rebuilt with TPI products back about 7 years ago, and it is a badass tranny and still is, but because of being parked more than driven throughout the years, it's leaking tranny fluid all over my garage floor. (no big suprise, as all older GM autos I have owned have done this at one time or another) Now, I usually have been just putting a quart when I want to drive it, and it runs great, but I need to fix this problem. My question is, do I need to get it completely rebuilt? Or what seals need to be replaced? It's got less than 2k miles since the rebuild. Of course the transmission guys I've talked to want to rebuild it completely, but it has very little miles. I'm just wondering if it's not just some seals I can replace. Thanks.